U.S. patent application number 13/586426 was filed with the patent office on 2013-02-21 for original document size detection device.
This patent application is currently assigned to NEC ENGINEERING, LTD.. The applicant listed for this patent is MASAYA IGAWA, SATOSHI KOMATSU, HIROYUKI OKADA, TAKAO SAKURAI, KOUSHI TAKANO. Invention is credited to MASAYA IGAWA, SATOSHI KOMATSU, HIROYUKI OKADA, TAKAO SAKURAI, KOUSHI TAKANO.
Application Number | 20130044334 13/586426 |
Document ID | / |
Family ID | 47712449 |
Filed Date | 2013-02-21 |
United States Patent
Application |
20130044334 |
Kind Code |
A1 |
IGAWA; MASAYA ; et
al. |
February 21, 2013 |
ORIGINAL DOCUMENT SIZE DETECTION DEVICE
Abstract
An original document size detection device of the present
invention is characterized by comprising a document reading table,
a light source which irradiates an original document placed on the
document reading table, a cover body which covers the original
document, a light detection unit which detects a reflected light
that a light from the light source is reflected by the original
document and an external light that enters the surface of the
document reading table when the cover body is lifted, a masking
unit which masks an output signal based on the external light in
the output signal of the light detection unit based on the
reflected light and the external light, and a determination unit
which determines a size of the original document in a main scanning
direction based on the output signal of the light detection unit
that is masked by the masking unit.
Inventors: |
IGAWA; MASAYA; (Shizuoka,
JP) ; KOMATSU; SATOSHI; (Tokyo, JP) ; OKADA;
HIROYUKI; (Tokyo, JP) ; TAKANO; KOUSHI;
(Tokyo, JP) ; SAKURAI; TAKAO; (Tokyo, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
IGAWA; MASAYA
KOMATSU; SATOSHI
OKADA; HIROYUKI
TAKANO; KOUSHI
SAKURAI; TAKAO |
Shizuoka
Tokyo
Tokyo
Tokyo
Tokyo |
|
JP
JP
JP
JP
JP |
|
|
Assignee: |
NEC ENGINEERING, LTD.
Tokyo
JP
NEC ACCESS TECHNICA, LTD.
Shizuoka
JP
|
Family ID: |
47712449 |
Appl. No.: |
13/586426 |
Filed: |
August 15, 2012 |
Current U.S.
Class: |
356/635 ;
356/625 |
Current CPC
Class: |
H04N 1/0071 20130101;
H04N 1/00748 20130101; H04N 1/00082 20130101; H04N 1/00737
20130101; G03G 15/607 20130101; G03G 2215/00329 20130101; H04N
1/00835 20130101; H04N 1/00013 20130101; H04N 1/00037 20130101;
H04N 2201/0081 20130101; H04N 1/00753 20130101 |
Class at
Publication: |
356/635 ;
356/625 |
International
Class: |
G01B 11/02 20060101
G01B011/02 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 16, 2011 |
JP |
2011-178064 |
Claims
1. An original document size detection device characterized by
comprising a document reading table, a light source which
irradiates an original document placed on the document reading
table, a cover body which covers the original document, a light
detection unit which detects a reflected light that a light from
the light source is reflected by the original document and an
external light that enters the surface of the document reading
table when the cover body is lifted, a masking unit which masks an
output signal based on the external light in the output signal of
the light detection unit based on the reflected light and the
external light, and a determination unit which determines a size of
the original document in a main scanning direction based on the
output signal of the light detection unit that is masked by the
masking unit.
2. The original document size detection device according to claim 1
characterized in that the determination unit determines that the
size of the original document in the main scanning direction is
maximum when an output signal of the light detection unit that is
masked by the masking unit remains in a High state in a masking
area and the size of the original document in the main scanning
direction is a size corresponding to a position at which the output
signal changes from the High state to the Low state when the output
signal of the light detection unit that is masked by the masking
unit does not remains in the High state in the masking area.
3. The original document size detection device according to claim 1
characterized in that the masking unit is means for masking an area
of the output signal that corresponds to an area between a position
between the maximum width of the original document in the main
scanning direction and the width of the original document having a
size that is one size smaller than the maximum width and a maximum
reading position in the main scanning direction.
4. The original document size detection device according to claim 1
characterized in that the reflected light is a reflected light
obtained when the light source is turned on when an opening angle
.alpha.1 of the cover body is from 5 degrees to 25 degrees, the
external light is an external light that enters the surface of the
document reading table when the opening angle .alpha.2 of the cover
body is from 4 degrees to 24 degrees, and wherein, 1 degree
<=.alpha.1-.alpha.2<=10 degrees.
5. The original document size detection device according to claim 1
characterized in that a hinge is used to open and close the cover
body and a hinge shaft is disposed at one edge side of the document
reading table along the sub-scanning direction perpendicular to the
main scanning direction of the original document.
6. An original document size detection device including a document
reading table, a light source which irradiates an original document
placed on the document reading table, a cover body which covers the
original document, light detection means, masking means, and
determination means characterized in that the light detection means
for detecting a reflected light that a light from the light source
is reflected by the original document and an external light that
enters the surface of the document reading table when the cover
body is lifted, the masking means for masking an output signal
based on the external light in the output signal of the light
detection means based on the reflected light and the external
light, and the determination means for determining a size of the
original document in a main scanning direction based on the output
signal of the light detection means that is masked by the masking
means.
Description
[0001] This application is based upon and claims the benefit of
priority from Japanese Patent Application No. 2011-178064, filed on
Aug. 16, 2011, the disclosure of which is incorporated herein in
its entirety by reference.
TECHNICAL FIELD
[0002] The present invention relates to an original document size
detection device.
BACKGROUND ART
[0003] A device such as a copier, a facsimile machine, or the like
has an image reading unit. The image reading unit includes an
optical module. The optical module includes for example, a light
source, a photoelectric conversion element (for example, a CCD), a
plurality of mirrors, and a lens. The light source irradiates an
original document placed on a document reading table. The light
emitted by the light source is reflected by the original document
and the reflected light is reflected by a mirror to lead it to the
CCD. The lens is disposed between the mirror and the CCD,
concentrates the light reflected by the mirror, and forms an image
on the CCD. A wire is connected to the both ends of the optical
module. A drum around which the wire is wound is driven by rotation
of a motor. Whereby, the wire is spooled, the optical module is
pulled in a sub-scanning direction (the sub-scanning direction is
perpendicular to a main scanning direction), and the optical module
is moved parallel to the original document in the sub-scanning
direction. By this, the image is read. When a cover body of an ADF
unit (automatic document feeder) is closed after the original
document is placed on the document reading table, the image reading
unit detects (determines) the size of the original document in both
the main scanning direction and the sub-scanning direction (the
width and the length of the original document are detected).
Namely, the size such as A4 size, A3 size, B4 size, or the like of
the original document placed on the document reading table is
determined.
[0004] The size of the original document in the main scanning
direction (the length of the original document) is
detected/determined based on a change in an output waveform of the
CCD that appears at a certain position when the optical module
reads the original document in the main scanning direction. The
output waveform of the CCD greatly changes at a boundary between an
area in which the original document exists and an area in which it
does not exist when the original document is read in the main
scanning direction. Namely, because the output waveform of the CCD
greatly changes at the boundary, it can be known that the position
at which the output waveform of the CCD greatly changes is the
position of the edge of the original document.
[0005] A size sensor disposed to a rail in the sub-scanning
direction on which the optical module moves is used for the
detection of the size of the original document in the sub-scanning
direction. A photo sensor composed of a pair of units (a light
emission unit and a light reception unit) is used for the size
sensor. The original document is detected by the size sensor as
follows. The light emission unit of the size sensor emits the
light, the original document is irradiated with the light, the
light is reflected by the original document, and when the light
reception unit of the size sensor receives the reflected light, it
is determined that the original document exists. When the reflected
light from the original document is not received by the light
reception unit of the size sensor, it is determined that the
original document does not exist. The size sensor is composed of a
plurality of photo sensors (for example, two photo sensors). The
size of the original document in the sub-scanning direction is
determined based on the combination of the signals from two photo
sensors.
[0006] The basic technology method for detecting (determining) the
size of the original document placed on the document reading table
has been explained above. When the sizes of the original document
in both the main scanning direction and the sub-scanning direction
are detected, a specific opening angle (closing angle) of the cover
body of the ADF unit is used as a trigger. For this reason, a cover
body angle detection mechanism is provided in a device in order to
achieve the detection of the size of the original document when the
closing angle of the cover body reaches the set angle (the specific
closing angle).
[0007] In the document size detection device disclosed in Japanese
Patent Application Laid-Open No. 2004-126132 (hereinafter, patent
document 1), in order to improve accuracy of detection of the size
of the original document in the main scanning direction in which
countermeasures against external light are provided for the
detection of the size of the original document, the detection of
the size of the original document in the main scanning direction is
achieved when the closing angle of the cover body reaches a certain
angle when the cover body is closed. The light source of the
optical module is turned off just before achieving the detection of
the size of the original document in the main scanning direction,
the output of the CCD is read while keeping this state, an incident
position of the external light is detected, and this is removed. As
a result, the influence of the external light is removed.
[0008] In the document size detecting device disclosed in Japanese
Patent Application Laid-Open No. 2004-258386 (hereinafter, patent
document 2), a scanner controller detects two opening angles, that
are a first stage opening angle and a second stage opening angle,
of the original document pressing plate based on a state of the
optical sensor and when the detected angle is within a range of the
first stage opening angle, it turns on a power supply of the light
source, the CCD, and an original document size detection sensor as
an original document size detection preparation process. Next, when
the opening angle of the original document pressing plate is within
a range of the second stage opening angle, the size of the original
document in the sub-scanning direction is determined, it is
determined whether or not the reflected light from the original
document exists based on a threshold value set in advance, and when
it is determined that the reflected light exists at a point, it is
determined that the original document exists at the point. As a
result, because the size of the original document can be detected
at a low opening angle of the original document pressing plate and
the most suitable angle in accordance with a closing operation of
the original document pressing plate performed by a user, the
original document size detection can be correctly performed while
reducing an erroneous detection due to the external light.
[0009] In Japanese Patent Application Laid-Open No. 2007-139607
(hereinafter, patent document 3), a sensor mounting structure
characterized in that a pair of transmission and reception
vibrators are held in a housing hole or by a housing holder in a
point-contact manner (or in a very light contact manner similar to
the point-contact manner) is disclosed. By this structure, the
vibration of the transmission/reception vibrators is less likely to
be transmitted to the housing hole or the housing holder and
whereby, a surface acoustic wave generated by one of the
transmission/reception vibrators is less likely to be transmitted
to the other transmission/reception vibrator (it is less likely to
act as disturbance).
[0010] However, in the device disclosed in patent document 1, the
CCD output is read twice, one is performed in a state in which the
light source is not turned on and the other is performed in a state
in which the light source is turned on, in a short time until the
lifted cover body is closed. For this reason, when the cover body
is quickly closed by an operator, the original document detection
cannot follow the lid closing speed and whereby, a false detection
occurs. Usually, it takes several milliseconds to several tens of
milliseconds until the CCD or the light source for the optical
module stably operates after the power is turned on. Moreover,
because the number of times of reading the CCD output increases, a
software process becomes complicated. In patent document 2 or 3,
means to solve the above-mentioned problem are not disclosed.
SUMMARY
[0011] An object of the present invention is to provide an original
document size detection device which can easily and correctly
determine a size of an original document in a main scanning
direction.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] Exemplary features and advantages of the present invention
will become apparent from the following detailed description when
taken with the accompanying drawings in which:
[0013] FIG. 1 is a block diagram of an original document size
detection device,
[0014] FIG. 2 is a figure showing a relation between a photo sensor
and a cover body opening angle,
[0015] FIG. 3 is an explanatory drawing showing a method for
mounting an actuator unit that acts as a cover body angle detection
mechanism,
[0016] FIG. 4 is a side view showing a method for mounting a
transmissive photo sensor,
[0017] FIG. 5 is a front view showing a method for mounting a
transmissive photo sensor,
[0018] FIG. 6 is an explanatory drawing showing a relation between
a transmissive photo sensor and a shield plate when a cover body
opening angle .alpha.>18 degrees,
[0019] FIG. 7 is an explanatory drawing showing a relation between
a transmissive photo sensor and a shield plate when a cover body
opening angle .alpha.=18 degrees,
[0020] FIG. 8 is an explanatory drawing showing a relation between
a transmissive photo sensor and a shield plate when a cover body
opening angle .alpha.=12 degrees,
[0021] FIG. 9 is an explanatory drawing showing a relation between
a transmissive photo sensor and a shield plate when a cover body
opening angle .alpha.=0 degree,
[0022] FIG. 10 is a schematic perspective view of an original
document size detection device in a cover body open state,
[0023] FIG. 11 is a schematic perspective view showing an internal
mechanism of an original document size detection device,
[0024] FIG. 12 is a figure showing an internal mechanism of an
original document size detection device,
[0025] FIG. 13 is a figure showing a method for mounting a
reflection type size sensor,
[0026] FIG. 14 is an explanatory drawing showing an external light
entering a surface of a document reading table of an original
document size detection device when a cover body is closed,
[0027] FIG. 15 shows a CCD output when an external light enters a
surface of a document reading table of an original document size
detection device,
[0028] FIG. 16 shows a CCD output when an external light enters a
surface of a document reading table of an original document size
detection device, and
[0029] FIG. 17 shows a CCD output when an external light enters a
surface of a document reading table of an original document size
detection device.
EXEMPLARY EMBODIMENT
[0030] Next, a detailed explanation will be given for a first
exemplary embodiment with reference to the drawings.
[0031] The original document size detection device according to the
present invention is installed in an image reading device such as
for example, a facsimile machine, a copier, a complex machine, or
the like. However, it is not limited to these devices.
[0032] The original document size detection device according to the
present invention has a function to automatically detect the sizes
of the original document in the main scanning direction and the
sub-scanning direction by an image reading device (for example, the
image reading device has the cover body which can be opened and
closed on the document reading table and reads an image of the
original document placed on the document reading table by moving
the CCD arranged in the main scanning direction of the original
document in the sub-scanning direction).
[0033] FIG. 1 is a block diagram of an original document size
detection device according to the present invention. The original
document size detection device according to the present invention
comprises a document reading table 7, a light source 24 which
irradiates an original document 13 placed on the document reading
table 7, a cover body (a document lid) 3 which covers the original
document 13 placed on the document reading table 7, a light
detection unit (for example, a CCD) 25 which detects a light that
is emitted by the light source 24 and reflected by the original
document 13 placed on the document reading table 7 and an external
light entering the surface of the document reading table 7 when the
cover body 3 is lifted, a masking unit 4 which masks an output
signal based on the external light in an output signal of the light
detection unit (CCD) 25 based on the reflected light and the
external light, and a determination unit 5 which determines a size
of the original document 13 in the main scanning direction based on
the output signal of the light detection unit 25 that is masked by
the masking unit 4.
[0034] In the present invention, the masking unit 4 is an essential
component. That is because when the external light enters the
surface of the document reading table, there is a high possibility
that the size of the original document is erroneously determined.
For example, when the external light enters the surface of the
document reading table and the masking unit 4 is not used, the
output signal of the light detection unit (CCD) 25 is shown in FIG.
15. In this case, the reason, either the original document 13
placed on the document reading table 7 is colored in black or the
external light enters the surface of the document reading table 7,
why the output signal shown in FIG. 15 is obtained cannot be known.
Namely, it is difficult to correctly determine the size of the
original document.
[0035] The masking unit 4 facilitates correct determination of an
original document end corresponding portion (a output waveform end
portion) 29a with respect to information (a CCD output waveform 29)
obtained by performing a photoelectric conversion of the light
reflected by the original document 13 that is read by the CCD 25.
When the masking unit 4 performs an electric process to the CCD
output information, a desired area of the CCD output waveform 29 is
masked. The size of the original document 13 in the main scanning
direction is determined based on the CCD output information masked
by the masking unit 4.
[0036] The masking unit 4 is configured as follows. For example,
the masking unit 4 masks an output signal in an area that
corresponds to an area between a position between the edge of the
original document having the maximum width in the main scanning
direction and the edge of the original document having a width that
is one size smaller than the maximum width and a maximum reading
position in the main scanning direction. The area masked by the
masking unit 4 is the area in which the output signal based on the
external light is generated when the cover body 3 is lifted by a
certain opening angle (the opening angle of the cover body 3 at
which the size of the original document in the main scanning
direction is determined: for example, .alpha.2, mentioned later)
and the external light enters the surface of the document reading
table 7. Further, the masking area can be determined by checking
the CCD output signal caused by the incident external light in
advance when the cover body 3 is lifted by the certain opening
angle.
[0037] The determination unit 5 is a computer for example, a CPU.
For example, the determination unit 5 operates as follows. When the
output signal of the light detection unit 25 that is masked by the
masking unit 4 remains in a High state in the masking area, it is
determined that the size of the original document 13 in the main
scanning direction is maximum. When the output signal of the light
detection unit 25 that is masked by the masking unit 4 does not
remain in the High state in the masking area, it is determined that
the size of the original document 13 in the main scanning direction
is a size corresponding to a position at which the output signal
changes from the High state to the Low state.
[0038] The original document size detection device of the present
invention will be described in detail below. The original document
size detection device has at least the above-mentioned
configuration. Namely, the original document size detection device
comprises the document reading table, the light source which
irradiates the original document placed on the document reading
table, the cover body which covers the original document placed on
the document reading table, the light detection unit which detects
a light that is emitted by the light source and reflected by the
original document placed on the document reading table and an
external light entering the surface of the document reading table
when the cover body is lifted, the masking unit which masks the
output signal based on the external light in the output signal of
the light detection unit based on the reflected light and the
external light, and the determination unit which determines the
size of the original document in the main scanning direction based
on the output signal of the light detection unit that is masked by
the masking unit. Therefore, the original document size detection
device which can easily and correctly determine the size of the
original document in the main scanning direction can be
provided.
[0039] The actuator unit 33 is provided as the opening angle
detection mechanism of the cover body 3. The actuator unit 33 is
configured for example, as shown in FIG. 3.
[0040] The actuator unit 33 includes the shield plates 35 (a first
shield plate 35a and a second shield plate 35bc) for blocking
(intercepting) or transmitting (receiving) the light of the
transmissive photo sensor 32. Further, the actuator unit 33
includes the base 37, a rod 34, and a spring 36. The rod 34 is
upwardly urged by the spring 36. When the cover body 3 is in a
closed state or in a closing state, it is in contact with the end
of the rod 34. Accordingly, the position of the rod 34 in a
vertical direction relates to the closing angle (the opening angle)
of the cover body 3. Namely, the rod 34 moves up and down in
conjunction with the opening/closing operation of the cover body 3.
However, in a state in which the cover body 3 is greatly opened by
for example, 90 degrees (an angle smaller than 90 degrees may be
applied), even when a pressing pressure from the cover body 3 side
does not act on the upper end of the rod 34 and an upward urging
force is applied to the rod 34 by the spring 36, the rod 34 does
not come off. In order to perform this operation, for example, a
structure in which a part of the actuator unit 33 is latched at a
proper position of the base 37 or the chassis 38 and whereby, the
rod 34 cannot move upward any more is used. For example, a
structure in which the shield plates 35 (35a and 35bc) cannot move
upward from a position shown in FIG. 6 is used.
[0041] Three transmissive photo sensors 32 (32a, 32b, and 32c)
attached to the chassis 38 are sandwiched between the base 37 of
the actuator unit 33 and the chassis 38 in order to prevent the
rise of three transmissive photo sensors 32 (32a, 32b, and 32c). By
this, even when an external force (for example, dropping) is
applied to the transmissive photo sensors 32 at the time of the
transport, the trouble such as the coming-off or the dropping of
the transmissive photo sensors 32 hardly occurs.
[0042] In more detail, the transmissive photo sensor 32 is fixed as
follows. As shown in FIG. 4, a hole is provided to a chassis 38. A
latching claw of the transmissive photo sensor 32 is inserted in
this hole. By this, the transmissive photo sensor 32 is latched
(fixed) to the chassis 38. If the transmissive photo sensor 32 is
used in this condition, there is a possibility that the latching
claw is unlatched by an external force because the transmissive
photo sensor 32 is only hooked in the hole by the latching claw. To
prevent this problem, a base 37 of the actuator unit 33 including
two shield plates 35 is pushed so as to make contact with the
transmissive photo sensor 32. Whereby, the actuator unit 33 is
inserted into a hole 49 of the chassis 38. Namely, the transmissive
photo sensor 32 is disposed so that it is sandwiched between the
base 37 and the chassis 38. After this, the actuator unit 33 is
fixed to the chassis 38 with a screw 50. By using the
above-mentioned structure, the transmissive photo sensor 32 is
firmly fixed to the chassis 38 without looseness.
[0043] It is desirable that the first photo sensor 32a, the second
photo sensor 32b, and the third photo sensor 33b are arranged on
the different lines in the vertical direction. It is desirable that
the second photo sensor 32b and the third photo sensor 33c are
arranged at the positions whose heights are different from each
other on the same line in the vertical direction.
[0044] In this device, three photo sensors are operated according
to the opening angle (closing angle) of the cover body 3 as shown
in the operation table of FIG. 2A or FIG. 2B. For example, with the
closing operation of the cover body 3, three photo sensors are
operated by a shield plate 35 according to the operation table of
FIG. 2A or FIG. 2B. The determination unit 5 determines the size of
the original document 13 in the sub-scanning direction based on the
output signal of the light detection unit 25 when the opening angle
(closing angle) of the cover body 3 is .alpha.1. The size of the
original document 13 in the main scanning direction is determined
when the opening angle (closing angle) of the cover body 3 is
.alpha.2 (.alpha.1>.alpha.2). By using the above-mentioned
configuration, only one interrupt port is enough for the detection
of the cover body angle. In the original document size detection
device according to the present invention, an angle range between 5
and 25 degrees is desirable for the angle .alpha.1 and the angle
range between 12 and 22 degrees is further desirable for the angle
.alpha.1. The angle range between 4 and 24 degrees is desirable for
the angle .alpha.2 and the angle range between 8 and 18 degrees is
further desirable for the angle .alpha.2. Here,
.alpha.1>.alpha.2. The angle range between 1 and 10 degrees is
desirable for the angle of (.alpha.1-.alpha.2) and the angle range
between 4 and 8 degrees is further desirable for the angle of
(.alpha.1-.alpha.2). The reason that the above-mentioned range is
desirable is described below. When the angle .alpha.1 is too large,
for example, the influence of the external light becomes excessive
and there is a high possibility that the size of the original
document is erroneously detected. When the angle .alpha.2 is too
small, a transition time from the original document size detection
operation to the next operation is too short and whereby, there is
a high possibility that the size of the original document is
erroneously detected. As a result of various experiments, when the
angle is within the above-mentioned range, there was a small
possibility that the size of the original document is erroneously
detected.
[0045] Namely, the opening angle (the closing angle) of the cover
body 3 is set so that the output signal due to the external light
28 can be masked.
[0046] For the purpose of accuracy improvement of the original
document size detection in the main scanning direction in which the
countermeasure against the external light is taken for the original
document size detection, in patent document 1, when the cover body
is closed, the size in the main scanning direction is detected when
the angle of the cover body reaches a predetermined angle. The
light source of the optical module is turned off just before
detecting the size of the original document in the main scanning
direction and after this, the CCD output is read, an incident
position of the external light is detected, and this is removed. By
this, the influence of the external light is removed. However, in
the device disclosed in patent document 1, the CCD output is read
twice, one is performed in a state in which the light source is
turned off and the other is performed in a state in which the light
source is turned on, in a short time until the lifted cover body is
closed. For this reason, when the cover body is quickly closed by
the operator, the original document detection cannot follow the lid
closing speed and whereby, a false detection occurs. Usually, it
takes several milliseconds to several tens of milliseconds until
the CCD or the light source for the optical module stably operates
after the power is turned on. Moreover, because the number of times
of reading the CCD output increases, a software process becomes
complicated.
[0047] In contrast, in the device according to the present
invention, the angle of the cover body is set so that the output
signal in an area that corresponds to the area on the surface of
the document reading table which the external light enters is
masked by the electric masking process. Accordingly, it is not
necessary to confirm the CCD output in advance in order to detect
the incident position of the external light 28. In a process for
confirming the CCD output waveform for original document size
detection in the main scanning direction, the masking process is
performed by deleting only the output waveform data in an area that
corresponds to the external light incident area. Therefore, a load
on software control for deleting the data in the area that
corresponds to the external light incident area does not become
especially large. Of course, because the data in the area that
corresponds to the external light incident area is excluded by the
masking, the influence of the external light 28 can be removed.
Accordingly, the influence of the external light is removed by
performing a few process and the original document size detection
determination can be performed with high accuracy.
[0048] In the original document size detection device according to
the present invention, it is desirable that when the closing angle
of the cover body 3 is equal to the angle .alpha.1, the light
source 24 is turned on. A configuration in which the reflected
light is detected by the light detection unit 25 and the
determination unit 5 determines the size of the original document
based on the output signal of the light detection unit 25 is
used.
[0049] The first shield plate 35a and the second shield plate 35bc
have a notch. The first photo sensor 32a is operated according to
the operation table of FIG. 2A (or FIG. 2B) by the operation of the
first shield plate 35a with the notch. The second photo sensor and
the third photo sensor 32c are operated according to the operation
table of FIG. 2A (or FIG. 2B) by the operation of the second shield
plate 35bc with the notch.
[0050] Three transmissive photo sensors 32 (the first photo sensor
32a, the second photo sensor 32b, and the third photo sensor 32c)
and two shield plates 35 (35a and 35bc) are configured as follows.
The second photo sensor 32b and the third photo sensor 32c are
disposed at a side of the first photo sensor 32a. The second photo
sensor 32b and the third photo sensor 32c are disposed on the same
line in the vertical direction. The shield plate 35a with the notch
is disposed at a location corresponding to the first photo sensor
32a. The shield plate 35a that moves upward and downward blocks
(intercepts) or transmits (receives) the light of the first photo
sensor 32a according to the position (the height) of the shield
plate 35a. The shield plate 35bc with the notch is disposed at a
location corresponding to the second photo sensor 32b and the third
photo sensor 32c. The shield plate 35bc that moves upward and
downward blocks (intercepts) or transmits (receives) the lights of
the second photo sensor 32b and the third photo sensor 32c
according to the position (the height) of the shield plate 35bc. In
particular, as shown in FIG. 6, the shield plate 35 and the
transmissive photo sensor 32 are disposed (arranged) so that the
shield plates 35 (35a and 35bc) does not block (intercept) the
lights of the transmissive photo sensors 32 (the first photo sensor
32a, the second photo sensor 32b, and the third photo sensor 32c)
when the cover body 3 is sufficiently lifted.
[0051] The shield plate 35 and the transmissive photo sensors 32
are disposed (arranged) so that the positional relationship shown
in FIG. 7 is obtained when the cover body opening angle is equal to
the angle .alpha.1 (for example, 18 degrees) when the cover body 3
is closed. Namely, the shield plate 35a is disposed (arranged) so
as to start to block (intercept) the light of the first photo
sensor 32a. Further, the shield plate 35bc is disposed (arranged)
so as not to block (intercept) the light of the second photo sensor
32b and the third photo sensor 32c.
[0052] When the cover body 3 is further closed, the shield plate 35
and the transmissive photo sensor 32 are disposed (arranged) so
that the positional relationship shown in FIG. 8 is obtained when
the cover body opening angle is equal to the angle .alpha.2 (for
example, 12 degrees). Namely, because the light of the first photo
sensor 32a starts to pass through the notch of the shield plate
35a, the state of the first photo sensor 32a changes from a light
shielding (blocking) state to the light receiving state and the
state of the second photo sensor 32b changes from the light
receiving state to the light shielding (blocking) state by the
shield plate 35bc. However, the third photo sensor 32c still
remains in the light receiving state.
[0053] When the cover body 3 is completely closed (the cover body
opening angle is 0 degree), the shield plate 35 and the
transmissive photo sensor 32 are disposed (arranged) so that the
positional relationship shown in FIG. 9 is obtained. Namely,
because the light of the first photo sensor 32a passes through the
notch of the shield plate 35a, the first photo sensor 32a remains
in the light receiving state and the second photo sensor 32b still
remains in the light shielding (blocking) state by the shield plate
35bc. However, the state of the third photo sensor 32c that has
been in the light receiving state is changed to the light shielding
(blocking) state by the shield plate 35bc.
[0054] As a result, the first transmissive photo sensor 32a, the
transmissive second photo sensor 32b, and the third transmissive
photo sensor 32c are set to a state (Low (light receiving state) or
High (light shielding state)) according to the operation table of
FIG. 2A by two shield plates 35 (35a and 35bc) that move upward and
downward together with the rod 34 that moves upward and downward in
conjunction with the closing angle (the opening angle) of the cover
body 3. In the above-mentioned specific example that is composed of
three photo sensors 32a, 32b, and 32c and two shield plates 35a and
35bc, the angle .alpha.1 of 18 degrees and the angle .alpha.2 of 12
degrees are used. After the original document 13 is placed on the
document reading table 7, the cover body 3 is closed. At the time
of starting to close the cover body 3, the positional relationship
between three photo sensors 32a, 32b, and 32c and two shield plates
35a and 35bc is shown in FIG. 6. At this time, the shield plates
35a and 35bc do not reach the positions of the photo sensors 32a,
32b, and 32c. Accordingly, in all the photo sensors 32a, 32b, and
32c, the light reception unit receives the light emitted by the
light emission unit. In this state, the output of the photo sensors
32a, 32b, and 32c is "Low". The output remains in the "Low" state
(in all the photo sensors 32a, 32b, and 32c, the light reception
unit receives the light emitted by the light emission unit) until
the opening angle (the closing angle) of the cover body 3 becomes
equal to 18 degrees.
[0055] When the opening angle (the closing angle) of the cover body
3 reaches 18 degrees, the lower end of the shield plate 35a blocks
the light emitted by the light emission unit of the photo sensor
32a (refer to FIG. 7). By this, the output of the first photo
sensor 32a is changed (switched) from "Low" to "High". However, in
the second photo sensor 32b and the third photo sensor 32c, because
the shield plate 35bc does not block the light emitted by the light
emission unit of each of the photo sensors 32b and 32c, the light
emitted by the light emission unit is received by the light
reception unit of each of the photo sensors 32b and 32c.
Accordingly, the output of the photo sensor 32b and the output of
the photo sensor 32c are still "Low". When the output of the second
photo sensor 32b and the output of the third photo sensor 32c are
"Low" and the output of the first photo sensor 32a changes from
"Low" to "High", the opening angle (the closing angle) of the cover
body 3 is equal to the angle .alpha.1 (for example, 18 degrees).
The cover body 3 is further closed. The output state of each of
three photo sensors 32a, 32b, and 32c is the same as the output
state when the opening angle (the closing angle) of the cover body
3 is equal to the angle .alpha.1 (for example, 18 degrees) until
the opening angle (the closing angle) of the cover body 3 reaches
the angle .alpha.2 (for example, 12 degrees).
[0056] When the opening angle (the closing angle) of the cover body
3 reaches the angle .alpha.2 (for example, 12 degrees), the
light-shielding by the shield plate 35a is released. Namely, in the
first photo sensor 32a, the light emitted by the light emission
unit is received by the light reception unit. Accordingly, the
output of the first photo sensor 32a is changed (switched) from
"High" to "Low". When the opening angle (the closing angle) of the
cover body 3 is equal to 12 degrees, the shield plate 35bc blocks
the light emitted by the light emission unit of the photo sensor
32b. By this, the output of the second photo sensor 32b is changed
(switched) from "Low" to "High". However, in the third photo sensor
32c, because the shield plate 35bc does not block the light emitted
by the light emission unit of the photo sensor 32c, the light
emitted by the light emission unit is received by the light
reception unit of the photo sensor 32c (refer to FIG. 8).
Accordingly, the output of the photo sensor 32c is still "Low".
[0057] The cover body 3 is further closed. The output state of each
of three photo sensors 32a, 32b, and 32c is the same as the output
state when the opening angle (the closing angle) of the cover body
3 is equal to 12 degrees before the cover body 3 is completely
closed. When the cover body 3 has been completely closed, the
output state of each of the first and second photo sensors 32a and
32b is not changed but in the third photo sensor, the light emitted
by the light emission unit of the third photo sensor is blocked by
the shield plate 35bc for the first time (refer to FIG. 9). Namely,
the output of the third photo sensor is changed (switched) from
"Low" to "High".
[0058] By using this mechanism, the transmissive photo sensor whose
price is low can be used without using the expensive proximity
switch. A magnet attached to the cover body 3 is not used. Further,
because the transmissive photo sensors 32 are disposed at the rear
side of the device, it is not necessary to extend a cable to the
front side of the device. Because the short cable can be used, the
cost of the device can be reduced. Moreover, a space or a structure
required for installation of the proximity switch and the magnet
that are provided at the front side of the image reading device is
not required.
[0059] A hinge is used to open and close the cover body 3. It is
desirable that a hinge shaft is disposed at one edge side of the
document reading table 13 along the sub-scanning direction (the
sub-scanning direction is perpendicular to the main scanning
direction) of the original document 13. It is desirable that the
above-mentioned shield plate 35 is disposed at the hinge shaft side
end of the cover body.
[0060] The original document size detection device according to the
present invention includes a movable optical module 22. The optical
module 22 includes the light source 24 which irradiates the
original document 13 placed on the document reading table 7 of an
image reading device 1. The optical module 22 includes a plurality
of mirrors 26 which reflects the light emitted by the light source
24 to lead it to a photoelectric conversion element (CCD) 25. The
optical module 22 includes a lens 23. The lens 23 is disposed
between the mirror 26 and the CCD 25, concentrates the light
reflected by the mirror 26, and forms an image on the CCD 25. In
order to move the optical module 22 in the sub-scanning direction
10, the optical module 22 is mounted on an upper portion of two
rails 43 that are disposed in a sub-scanning direction 10. A wire
40 is connected to the both ends of the optical module 22. In order
to move the optical module 22 in the sub-scanning direction 10 (it
is perpendicular to a main scanning direction 11), a drum 41 around
which the wire 40 is wound and a drive unit 42 which rotates the
drum 41 are provided.
[0061] Two reflection type size sensors 44 are used for the
detection of the size of the original document in the sub-scanning
direction 10. The reflection type size sensor 44 is composed of a
pair of units (a light emission unit 45 and a light reception unit
46). The reflection type size sensor 44 is held by two holders 48
fixed to the rail 43 that is a track for the optical module 22 in
the image reading device 1. In particular, the reflection type size
sensor 44 is obliquely fixed. Two reflection type size sensors 44
are mounted on a rectangular substrate 47 whose long side is along
the sub-scanning 10 direction.
[0062] The CCD output waveform based on the light that is emitted
by the light source 24 and reflected by the original document 13 is
used for the detection of the size of the original document in the
main scanning direction 11.
[0063] In the original document size detection device according to
the present invention, a load on software control does not become
especially large because the electric masking process is used.
Because the data in the external light incident area is excluded by
the masking, the influence of the external light is removed. The
influence of the external light is removed by performing a few
processes. Therefore, the accuracy of the original document
detection is improved.
[0064] For example, in Japanese Patent Application Laid-Open No.
2006-261848 (hereinafter, patent document 4), as a method for
detecting the size of the original document, a method in which when
it is detected that the angle of the cover body reaches a specified
angle, the light source is turned on by using this as a trigger,
the detection operation is delayed for a predetermined time by a
software-controlled timer until an amount of light emitted by the
light source is equal to a specified amount of light, and when the
predetermined time has elapsed, the reading is performed is
proposed. However, even when this method is used, when the cover
body is quickly closed by the operator, there is a case in which
the reading for size detection starts after the cover body has been
completely closed because of mismatch between the predetermined
time of the timer and the cover closing speed. For this reason,
there is a possibility that the false detection occurs. Further,
the angle of the cover body at which the reading starts is not
specified. Therefore, the angle of the cover body at which the
reading starts is different for each operator because the cover
body closing speed is different for each operator by individual
variability. As a result, the result of the size detection varies.
In the apparatus disclosed in patent document 4, only one angle can
be set with respect to the angle of the cover body that is used as
the trigger of the operation.
[0065] In contrast, in the device according to the present
invention, a plurality of angles of the cover body 3 that are used
as the trigger can be set. Namely, the cover body opening angle at
which the light source 24 is turned on and the cover body opening
angle at which the reading for size detection is performed can be
individually set. Therefore, the timing at which the light source
24 is turned on and the timing at which the reading is performed
can be controlled separately. Because the operations are started at
different timings, in other words, the operations are started at
different cover body opening angles, the reading can be performed
at the predetermined timing without relation to operator's lid
closing speed. As a result, the accuracy of the original document
size detection is improved.
[0066] It has been described above that the cover body closing
speed is different for each operator by individual variability. In
order to respond to various cover body closing speeds, the angle
detection is performed in an interrupt processing for detecting a
moment at which a signal of an angle sensor is switched. A method
in which one angle detection sensor is provided for each angle to
be detected and a moment at which each angle detection sensor is
switched is detected is known. However, in order to perform the
interrupt processing, it is necessary to set an interrupt detection
port at an initial stage of designing a substrate. Because the
total number of ports which can be set in the CPU is limited and
the number of ports required by the other function increases with
the increase of the number of functions provided for the device,
the interrupt detection port cannot be additionally provided. For
this reason, when the necessity of increasing or decreasing the
number of the original document size detection angles occurs, this
cannot be achieved. There is a possibility that the size of the
original document is erroneously detected.
[0067] The device according to the present invention uses the rod
with the shield plate 35 for example, as shown in FIG. 3. By this,
the trigger for angle detection is concentrated on only one photo
sensor 32a and the number of the interrupt detection ports is
reduced by one. A signal is switched with respect to the cover body
opening angle at which the original document size detection is
performed and when the interrupt processing is performed, the cover
body opening angle is determined based on the operation table of
FIGS. 2A and 2B. The number of the cover body opening angles that
have to be detected can be increased or decreased and whereby, the
size of the original document can be surely detected.
[0068] Next, the operation of the original document size detection
device according to the present invention will be described in
detail. The detection of the size of the original document is
performed by using the opening angle (the closing angle) a of the
cover body 3 as a trigger. When the lifted cover body 3 is
completely closed (.alpha.=0 degree), the following operations (1)
to (5) are performed: (1) the cover body is lifted, (2) the light
source is turned on (.alpha.=18 degrees), (3) the size of the
original document in the sub-scanning direction is detected
(.alpha.=18 degrees), (4) the size of the original document in the
main scanning direction is detected (.alpha.=12 degrees), and (5)
the cover body is completely closed (.alpha.=0 degree). The angle
.alpha. is detected by the mechanism for detecting the angle of the
cover body 3 that is composed of three transmissive photo sensors
32a, 32b, and 32c and the actuator unit 33 (especially, two shield
plates 35a and 35bc) and the above-mentioned operations (1), (2),
(3), (4), and (5) are performed in order.
[0069] The above-mentioned operation (1) will be described in more
detail. When the cover body 3 is sufficiently lifted, the rod 34 of
the actuator unit 33 is not pressed by the cover body 3. At this
time, because three transmissive photo sensors 32a, 32b, and 32c
are in the "light receiving state", the cover body 3 is in a state
shown as "cover body opening angle >.alpha.1 (for example, 18
degrees)" in FIG. 2A. Therefore, the CPU determines that the cover
body 3 is lifted.
[0070] After this, when the cover body 3 is closed, by the shield
plates 35a and 35bc fixed to the rod 34 that moves in conjunction
with the cover body 3, three transmissive photo sensors 32a, 32b,
and 32c are set to a state indicated in the column "cover body
opening angle=.alpha.1 (for example, 18 degrees)" of the operation
table in FIG. 2A. The CPU receives the output information on three
transmissive photo sensors 32a, 32b, and 32c when the cover body
opening angle is equal to the angle .alpha.1 (for example, 18
degrees) and determines that the opening angle (the closing angle)
of the cover body 3 is equal to the angle .alpha.1 (for example, 18
degrees). The CPU uses this as the trigger and turns on the light
source 24.
[0071] The size of the original document in the sub-scanning
direction 10 is detected by using the turn-on of the light source
24 as the trigger. Namely, the size of the original document in the
sub-scanning direction 10 is detected based on the output signals
of two size sensors 44. The method for detecting the size of the
original document in the sub-scanning direction 10 is same as the
conventional one. Therefore, the detailed explanation will be
omitted.
[0072] After this, when the cover body 3 is further closed, by the
shield plates 35a and 35bc fixed to the rod 34 that moves in
conjunction with the cover body 3, three transmissive photo sensors
32a, 32b, and 32c are set to a state indicated in the column "cover
body opening angle=.alpha.2 (for example, 12 degrees)" of the
operation table in FIG. 2A. The CPU receives the output information
on three transmissive photo sensors 32a, 32b, and 32c when the
cover body opening angle is equal to the angle .alpha.2 (for
example, 12 degrees) and determines that the opening angle (the
closing angle) of the cover body 3 is equal to the angle .alpha.2
(for example, 12 degrees).
[0073] The CPU uses this as the trigger and determines the state of
the CCD output waveform 29 of the light that is emitted by the
light source 24 that is turned on when the opening angle (the
closing angle) of the cover body 3 is equal to the angle .alpha.1
(for example, 18 degrees) and reflected by the original document
13. When the opening angle (the closing angle) of the cover body 3
is equal to the angle .alpha.2, the cover body 3 is not completely
closed. Therefore, the external light 28 enters a reading area on
the surface of the document reading table. Accordingly, the CCD 25
receives both the light reflected by the original document 13 and
the external light 28 and outputs the combined information. As
shown in FIG. 15, the combined information (CCD output waveform)
includes a convex waveform 30 caused by the external light 28.
However, in the device according to the present invention, the
masking unit 4 performs the electric masking process and the convex
waveform 30 is masked as shown in FIG. 16. The CPU determines that
the output waveform end portion 29a in the "High" state corresponds
to the edge of the original document in the main scanning direction
11. As a result, the size of the original document in the main
scanning direction 11 can be known.
[0074] However, as shown in FIG. 17, there is a case in which the
output waveform end portion in the "High" state is included in the
masking area. In such case, the CPU determines that the size of the
original document in the main scanning direction 11 is maximum.
Namely, by performing the electric masking process, the influence
of the external light is prevented and the erroneous detection of
the size of the original document caused by the external light 28
does not occur. Further, when detecting the output waveform end
portion 29a, the scanning is performed from the right end side (the
masking area side) in a figure showing the CCD output waveform.
That is because the detection time can be shortened.
[0075] After this, when the cover body 3 is further closed, by the
shield plates 35a and 35bc fixed to the rod 34 that moves in
conjunction with the cover body 3, three transmissive photo sensors
32a, 32b, and 32c are set to a state indicated in the column "cover
body opening angle=0 degree" of the operation table in FIG. 2A. At
this time, the CPU determines that the cover body 3 is completely
closed.
[0076] The operation effect of the original document size detection
device according to the present invention is shown below.
[0077] The size of the original document in the main scanning
direction 11 is detected as follows. For example, the edge of the
original document is discriminated by using the CCD output
waveform. At this time, because the external light is not
completely blocked by the cover body 3, there is a case in which
the external light 28 such as the light of a fluorescent lamp, the
light of the sun, or the like may enter the CCD. The CCD output
waveform is affected by this external light 28. As a result, the
erroneous detection of the size of the original document occurs.
Therefore, the masking unit 4 performs the masking process (for
example, the electric masking process) to the CCD output waveform
corresponding to an area in which the external light 28 enters.
Namely, even when the external light 28 enters, when the
determination unit 5 determines the size of the original document,
a region in which the CCD output waveform varies by the external
light 28 is excluded. As a result, the size of the original
document can be determined without being affected by the external
light 28.
[0078] For example, the image reading device such as a facsimile
machine, a copier, or the like usually uses a short focus lens
having a short optical path length from a viewpoint of weight
reduction, miniaturization, space saving, and cost reduction. The
short focus lens is used in the device according to the present
invention. Because the short focus lens has a wide field angle, the
view angle of the optical module is wide. This means that the
detection of the size of the original document is affected by the
external light (for example, the light of a fluorescent lamp
provided on a ceiling or the light of the sun) 28 which cannot be
blocked by the cover body 3 when the cover body 3 is being closed.
In other words, the external light 28 which is not blocked by the
cover body 3 enters the surface of the document reading table 7.
When the size of the original document in the main scanning
direction 11 is detected in this state, the waveform (the convex
waveform) caused by the external light 28 is generated in the CCD
output waveform when the original document 13 does not exist in an
area which the external light 28 enters and whereby, it is
erroneously determined that the position of the convex waveform end
is the position of the edge of the original document 13. Namely,
the position of the edge of the original document 13 cannot be
correctly detected.
[0079] To solve this problem, extension of the cover body 3 in a
direction toward a front side of the device (user side) may be
performed. Namely, when the cover body 3 is extended in a direction
toward the front side (user side) of the device, because the
external light 28 does not enter the surface of the document
reading table even when the cover body 3 is being closed, the
erroneous operation hardly occurs. However, when this method is
used, the size of the device becomes large. Accordingly, the
masking unit 4 performs the electric masking process for masking
the output waveform in an area that corresponds to the area on the
surface of the document reading table which the external light 28
enters. By this, the size of the original document can be correctly
detected even when the cover body 3 is not extended in the
direction toward the front side of the device (user side), in other
words, even when the external light 28 enters the surface of the
document reading table 7. By this process, the convex waveform is
electrically eliminated and the detection of the size of the
original document is not affected by the external light 28.
[0080] The electric masking process is applied to the output signal
in an area that corresponds to an area between a position between
the edge of the original document having the maximum width in the
main scanning direction and the edge of the original document
having a width that is one size smaller than the maximum width and
a maximum reading position in the main scanning direction. Namely,
the opening angle (the closing angle) of the cover body 3 when the
size of the original document in the main scanning direction is
detected is set so that the output signal due to the external light
is masked by the electric masking process. When the electric
masking process is applied to the output signal in the
above-mentioned area and the output signal does not remain in the
High state in the masking area, it is determined that the size of
the original document in the main scanning direction is a size
corresponding to a position at which the output signal changes from
the High state to the Low state. When the output signal remains in
the High state in the masking area, the edge of the original
document cannot be discriminated. Accordingly, in this case, it is
determined that the size of the original document is maximum. When
the original document size detection device is configured as
described above, it is not necessary to extend the cover body 3 in
the direction toward the front side of the device. Therefore, the
size of the device can be reduced. All sizes of the original
documents can be detected without being affected by the external
light 28.
[0081] Namely, an exemplary advantage according to the invention is
that the size of the original document in a main scanning direction
can be easily and correctly determined.
[0082] The previous description of embodiments is provided to
enable a person skilled in the art to make and use the present
invention. Moreover, various modifications to these exemplary
embodiments will be readily apparent to those skilled in the art,
and the generic principles and specific examples defined herein may
be applied to other embodiments without the use of inventive
faculty. Therefore, the present invention is not intended to be
limited to the exemplary embodiments described herein but is to be
accorded the widest scope as defined by the limitations of the
claims and equivalents.
[0083] Further, it is noted that the inventor's intent is to retain
all equivalents of the claimed invention even if the claims are
amended during prosecution.
* * * * *